Ammonia refrigerating apparatus



&487903 Nov. 1, 1949 R. s. TAYLOR ETAL AMMONIA REFRIGERATING APPARATUS 3 Sheets-Sheet 1 Filed April 6, 1946 R. S. TAYLOR ET AL AMMONIA REFRIGERATING APPARATUS Nov. 1, 1949 3 Sheets-Sheet 2 Filed April 6, 1946 Nov. E, 1949 R. s. TAYLOR ETAL AMMONIA REFRIGERATING APPARATIS Filed April 6, 1946 3 ShetS-Sheet 3 W? VJNI `NTORS Patenta! Nov. l, 1949 %487.001 AMMONIA. REFRIGERATING APPARATUS Robert S. Taylo Evasville, and Bernard A. Daley, Scott Township, Vanderburgh County, Ind., assigno's to Servei, Inc., New York, N. Y., a corporatio of Delawarc Application April 6, 1946, Serial No. %0,126

' p claim.

1 Our invention relates to iron reirlgeration a paratus.

such apparatus is constructed of iron or steel tubing and vessels joined together by an electric arc or a torch welding process or both. These,

processes require considerable work in testing for leaks and internal obstruction, and considerable work in handling and rewelding to correct leaks and occasional internal obstruction.

The object of our invention is to provide a new refrigeration apparatu of iron or steel and of which the various parts are joined together in a structurally strong and inherently leak proof manner. This is accomplished by 'so forming the parts as to be joined in a special manner and bonding the joints by a ferrous material but by a process which inherently efi'ects a complete seal.

It is a matter of general knowledge that eutectic mixtures or metals containing a melting point depressant are useful in various applications as a solder or sealing material as, for instance, an iron and phosphorus mixture for sealing metal vacuum tubes. Also a. matter of general knowledge is the use of copper in making a brazed joint in a reducing atmosphere. When the temperature is raised, the copper flows by capillarity and moves not only into the space between the parts being :Ioined but also penetrates the iron or steel parts being Joined, thus efiecting a tight and structurally strong joint. This so-called hydrogen brazing could not be used for refrigeration apparatus employing aqueous ammonia due to its chemical activity with respect to copper, nor for apparatus subject to electrolytic corrosion. This appears to be one reason why brazing has never been considered feasible for iron refrigeration apparatus. Also, since such apparatus utilizing amnonia has high internal pressures, mixtures such as iron and phosphorus have apparently been dismissed on account of brittleness ordinarily encountered when phosphorus is combined with iron.

We have found that iron containing phosphorus can be utilized for -joining and scaling iron reirigeration apparatus, provided the apparatus is so !ormed that deformation under internal pressure or external application oi: force occurs in wall structure of joined parts before such occurrence in the joints, and the alloy is of certain proportions and properly applied under certain temperature conditions. A satisfactory alloy is one consisting of iron containing phosphorus in a range from 9 to 15 per cent, this range includin: the first eutectlc which is about 10.2 per cent.

Strangely, unlike copper or any other ,known iron brazing material the iron-phosphorus alloy is self fluxing and can be used in the presence of oxygen.

Our invention is more fully described by refet.. ence to the accompanying drawings oi which:

Fig. 1 is a more or less schematic illustration of an ammonia refrigerating apparatus embodyi ing the invention:

Figs. 2, 3, 4, 5, and 7 are detail sectional views of certain joints in the apparatus of Fig. 1 before brazing;

Fig. 6 is a detail sectional View of the join of Fig. 5 after brazing;

Fig. 8 is a plan view of Fig. 7; and

Fig. 9 is a view like Fig. 'I showing the joint after brazing.

VReferring to Fig. 1 of the drawings, a generator o has a heating flue ll. A suitable bumer, not shown, is arranged so that its flame projects into the lower end of the fiue ll. The lower end of I a rectifler or analyzer pipe z is connected to the generator o. The upper end of the pipe l2 is connected by a conduit |3 to a finned condenser pipe 14. The generator lll is connected by a, vapor lift pipe IS to a separating vessel IG. 'Ihe upper part of the vessel I 6 is connected by a pipe ll to the rectifler |2. The lower part of the vessel !6 is connected by a conduit |8 to one passage of a liquid heat exchanger l9. The other passage of 'the liquid heat exchanger |9 is connected by a conduit 20 to the rectifier l2.

- An absorber 2! comprises a. finned pipe coil 22 and a storage vessel 23. The adsorber vessel 23 is connected to the liquid heat exchanger !9 by a pipe 24, and to the gas heat exchanger 25 by a, pipe 26. The absorber coil 22 is connected by a pipe 21 to the gas heat exchanger 25. The absorber coi is also connected by a portion of pipe 21 and a pipe 28 to the liquid heat exchanger l9.

A pipe coil type of evaporator 29 is located in an insulated refrigerator storage compartment 30. The upper end of the evaporator 29 is connected by a pipe 3l, a pipe 32, a gas heat exchanger 33, a pipe 34, the gas heat exchanger 25, and the pipe 21 to the upper end of the absorber coil 22. The lower end of the evaporator 29 is connected by a pipe 35, the gas heat exchanger 33, a pipe 36, the gas heat exchanger 25, and the pipe 26 to the absorber vessel 23.

The lower end of the condenser !4 is connected by a pipe 31 to the pipe 3! which communicates with the upper end of the evaporator 29. The condenser Il is provided with a vent pipe 38 which is connected from the high point ot the to the absorber vessel 23. The gas occupies that' part oi! the system above the level of solution therein.

In operation, heat is applied to the generator s. As known, this application of heat may be thermostatically controlled by a temperature condition afiected by the evaporator 29. Ammonia vapor is expeued from solution in the generator III. Some of the vapor flows from the generator through the rectifler l2 and the pipe la to the condenser l4. Some of the vapor rises through pipe IE causing lifting of liquid through this pipe into the vessel !6. This lifting or pumping vapor flows from the vessel IS through the pipe I' into the rectifier l2 and thence through the pipe i 3 to the condenser I 4.

The vapor in the condenser M condenses to liquid which flows from the lower end of the condenser pipe through the pipe 31 and the pipe 3! into the upper end of the evaporator 29. The liquid ammonia vaporizes in the evaporator 29, producing a refrigerating eiTect for cooling the refrigerator compartment 30. The ammonia vapor formed in the evaporator 29 difiuses into the hydrogen atmosphere, and the resulting mixture of hydrogen and ammonia vapor flows from the upper end of the evaporator 29 through the pipes 3! and 32, the gas heat exchanger 33, the pipe 36, the gas heat exchanger 25, the pipe 26, and the upper part of the vessel 23 into the absorber tube 22.

Weakened absorption liquid from the generator separating vessel !6 fiows through the pipe a, the liquid heat exchanger !9, the pipe 28, and the lower end of the pipe 21 into the upper end of the absorber tube 22. The absorption liquid flows downward through the pipe 22 into the absorber vessel 23. Th liquid absorbs ammonia vapor in the pipe 22 and the resulting enriched solution flows from the absorber vessel 23 through the pipe 24, the liquid heat exchanger !9, the pipe 20, and the rectifier |2 to the generator The weak gas fiows from the absorber tube 22 through the pipe 21, the gas heat exchanger 25, the pipe 34, the gas heat exchanger 33, and the pipe 35 to the lower end of the evaporator 29.

Non-condensible gas fiows from the condenser |4 through the vent pipe 38 to the previously described gas circuit. The vessel 39 in the vent pipe 38 provides for a reserve quantity of hydrogen which upon increase in pressure in the system under high temperature conditions is displaced by ammonia vapor from the condenser I 4, the displaced gas flowing into the gas circuit so that refrigeration continues under the higher pressure conditions without breathing of ammonia' vapor into the gas circuit.

Fig. 2 is an enarged sectiona view illustrating how an end of the generator Io is fabricated. The t flue pipe l I is located concentrically within a casing tube 40. The flue pipe projects beyond the end of the casing tube. An end plate 4l has one portion 42 which overlaps the end of the casing tube 40, and another portion 43 which forms a sleeve around the flue pipe II. The portion 42 of the end plate 4! overlaps and in en'ect als o forms a sleeve over the end of the casing tube 40. These iapped or sleeve joints are a characteristic of the present invention. Although for' the purpose of clarity the drawing indicates considerable clearance, the joints should be between a force fit and a .015 inch ciearance. The same applies to all of the joints in the subject apparatus. Witha joint of this character the walls oi the apparatus parts. such as wall 40 or the flue pipe ll, would deform under internal pressure or external application of force before such occurrence at the double wall joint. A rin 44 of brazing metal is located around the casing tube 40 adjacent the sleeve joint between this casing and the plate portion 42. Another ring 45 of brazing material is located on the fiue pipell next the sleeve joint between the fiue pipe and the end plate portion 43.

The brazing rings 44 and 45 are made in accordance with an invention of B. A. Daey described in his co-pending application serial No. 660,188 filed concurrently herewith. This type of brazing ring is made by a process generally known in powder metallurgy and consists in compacting the ring from constituents in powder form. The brazing ring is an iron-phosphorus composition of 9 per cent phosphorus. The temperature at the joint is raised to a value between 2050 F. to 2100 F., this being above the melting temperature of the brazing material, and below the melting point of the iron. The material of the brazing ring melts and distributes itself by capillarity throughout the face area of each iapped or sleeve joint, and forms a fiilet at each edge of the joint, as hereinafter described in connection with Figs. 5 and 6.'

Fig. 3 is an enlarged sectiona view illustrating how the top of the separating vessel IG is fabricated. An inverted cup 43 is fitted in the upper end oi' a tube forming the vessel !6, the side wall of the cup 46 and the wall of the tube s forming a iapped or sleeve type joint. A ring 41 of brazing material is-shown located next one edge of the sleeve joint so that when the tempera- I formed. The pipe I'I projects upward concen-.

trically within the tube !6. The lower endof the tube IG is drawn or otherwise suitably formed into a neck which forms a sleeve joint with the pipe l'l. A ring 48 of brazing material is shown located adjacent the lower edge of this sleeve joint. Upon increase in temperature, the material of the ring. melts and flows by capillarity throughout the joint.

Fig. 5 is an enlarged'sectional view illustrating how a section of the condenser pipe |4 and. the absorber pipe 22 is fabriated. The condenser pipe l4 is made up of a plurality of nested cups 49, the rims of these cups forming the heat radiation fins. The nested cups 49 form a series of sleeve joints 'adjacent each of which there is located a'ring 50 of brazing material. When the temperature is raised above the melting point of the brazing material, the latter fiows by capillarit throughout each sleeve joint formin a thin film of bonding material in the joint and a fillet Fle. 'I is an enlarged sectional view illustrating `between a force fit and a .015 inch clearance.

Thus constructed and arranged, these parts so reinforce each other at the joint that deformation under internal pressure or external application of force must first occur in wall portions 'other than those at the joint. This construction and arrangement also provides a joint which is capillary to the molten iron-phosphorus composition. This composition is provided in the form of a ring 53 located around the pipe on top of the Washer 52 as may be seen in Fig. 7 and the top view Fig. 8. When the temperature is raised above the melting point of the iron-phosphorus composition it flows into the capillary regions between the iron parts !9, 20, and 52, and distributes itself by capillarity throughout these regions forming a film, illustrated in enlarged cross section in Fig. 9, which projects as a dispersion in the metal of the contiguous wall surfaces of the parts !9, 20, and 52.

A few oi' the joints in the apparatus have been described in detail to illustrate how the invention is carried out. It will now be understood that all of the joints have to be specially formed in the practice oi' this invention. A principal requirement of the special formation is the iap or sleeve type of relationship between the parts being joined, and a relatively tight fit for the purpose of causing both reinforcement against deiormation at the joint and complete distribution of the I bonding material throughout the joint by capillarity. The appearance of afillet completely around each edge of the joint, as may be seenin made by building up a body of iron for scaling the joint and joining togeher the adjacent iron parts. A welded joint, the only fusion type o! joint heretofore known in iron 'refrigerating apparatus, requires human skill and control and is therefore subject to leaking and requires considerable work in testing for leaks, and rewelding. After rewelding to correct a leaky joint, testing is again necessary, and this process o! rewelding and leak testing is repeated until all units have satisi'actorily passed the leak test. This is a considerable item of cost which is reflected in the price of such product paid by the public'. The value oi' the present invention is not that it decreases the amount of cost occasioned by leal: testing. but that' it completely eliminates the 6 necessity for leak testing. It has been found that a joint made in accordance with this invention does not leak, nor do any of a hundred joints leak.

Applying iron-phosphorus brazing material of 9 per cent phosphorus, joints have been made in ammona refrigerating apparatus which withstand over 2500 lbs. per sq. in. internal pressure and remain leak proof. The brazing temperature using such material is preferably between 2050 F. and 2100 F. Photomicrographs of joints made under these conditions show there is dispersion of the bonding material into the contiguous walls of the' Joined parts. such mierographs also show that the bonding material forms a film that is an unbroken solid throughout the joint area. Thus it is that such a joint has such strength and is leak proof.

Although we have described a specific form of brazing ring, it should be. understood that the brazing material can be applied in other ways. For instance, powdered alloy can be mixed with a binder to form a. paste, or the powder can be retained in a sac of ash free material such as pyroxylin or other nitrocellulose lacquer. It can be made in the form of pellets or tablets for application to a joint, because, if the joint is properly'formed, the material flows throughout the joint by capillarity when the melting point of the material is exceeded. The ring formed is .of course highly advantageous in quantity production.

Various other modifications and changes may be made within the scope of the invention as set forth in the following claim.

We claim:

Ammonia refrigeration apparatus comprising iron parts joined together and having walls constructed and arranged to so mutually reinforce the joint forming portions thereof that deformation under fluid pressure or other application of force must first occur in other portions thereoi, the joints being capillary to molten iron-phosphorus composition at a temperature above the melting point of the composition and below the melting point of the iron parts, and sealed by such composition in solid phase in the form of a film in each capillary region projecting as a dispersion in the metal of the contizuous wall portions.

. ROBERT S. TAYLOR. BERNARD A. DALEY.

REFEREN CES CITED The following reterences are ot record in the flle of this patent:

UNITED STATES PA'IENTS 

